In connection with optical scanning devices used for image output apparatuses such as laser printers, copiers, or facsimile machines, techniques for increasing a scan angle have been proposed or put to practical use.
These techniques include an optical scanning device described in Patent Document 1. FIG. 1 is a diagram showing the configuration of the optical scanning device.
In FIG. 1, a transfer optical system includes concave mirror 671 with a plane of reflection directed toward scan mirror 651, and lens 672 located between concave mirror 671 and scan mirror 651. A light beam scanned by scan mirror 651 is guided to concave mirror 671 via lens 672. Furthermore, the light beam folded back by concave mirror 671 is guided to scan mirror 651 via lens 672. Thus, the light beam is scanned by scan mirror 651 again, and the resultant light beam is emitted toward a scan target surface. As a result, the scan angle of the emitted light beam is increased.
Patent Document 1: JP2005-62358A